Technical Abstract:
The effect of chromium (Cr; KemTRACE®brandChromiumProprionate 0.04%, Kemin Industries) supplementation on the metabolic response to LPS challenge was examined. Steers (n=20; 235±4 kg body weight (BW)) received a premix that added 0 (Con) or 0.2 mg/kg Cr to the total diet (DM (dry matter) basis) for 55d. Jugular catheters were placed prior to challenge. Blood samples were collected every 30 min from -2 to 8, and at 24h relative to LPS (lipopolysaccharide)challenge (0.5 ug/kg BW). Individual BW were recorded at cannulation, and 24h and 7d post-LPS. Concentrations of glucose, insulin, and non-esterified fatty acid (NEFA) were measured. Data were analyzed using the Mixed procedure of SAS specific for repeated measures with fixed effects of treatment (trt), time, and their interaction. Initial BW did not differ (P=0.37) for Cr (314±8 kg) and Con (324±8 kg). Twenty-four hours post-LPS, Cr steers had lost less weight (P=0.03; -7±2 kg) than Con steers (-14±2 kg). Overall, Con steers tended to lose weight (initial compared to 7d post-LPS BW; -2.4±3.6 kg) and Cr steers tended to gain weight (6.4±3.6 kg; trt P=0.09). Pre-LPS glucose did not differ for Con and Cr steers (P=0.97). Post-LPS there was a time x trt interaction (P<0.01) in that glucose peaked within 0.5h in Cr (153±4 mg/dL) but not Con (111±4 mg/dL) steers. Glucose then decreased in Cr steers and also decreased in Con steers at 2h compared to baseline (P<0.01). Insulin concentrations were not different between trt pre-LPS (P=0.63). Post-LPS insulin increased (P<0.01), peaking at 2h before returning to baseline. There was a trend for insulin to be greater in Con (1.1±0.1 ng/mL) than Cr (0.9±0.1 ng/mL) steers (P=0.13). Concentrations of NEFA did not differ pre-LPS (P=0.54). Post-LPS NEFA increased (P<0.01), with Cr steers producing greater peak NEFA (0.21±0.02 nmol/L) at 0.5h than Con steers (0.16±0.02 nmol/L; P<0.04). Following peak values, NEFA decreased before increasing again at 3.5h in Cr (P=0.04) and 4h in Con (P<0.01), and remained elevated 24h post-LPS. These data suggest supplementation of Cr enhanced the availability of energy resources, attenuated weight loss, and allowed for a quicker recovery following LPS challenge.